The ACGIH, with the technical input of its Air Sampling Instruments committee, is sponsoring a symposium entitled: ACGIH Symposium on Air Sampling Instruments: Applications, Technology, Criteria and Standards. A symposium would be an ideal forum for bringing worldwide interests together, all at one time and in one place. Distinctions and separations between air measurements for purposes of industrial hygiene, air pollution, indoor air, health physics, hazardous waste, etc. are rapidly disappearing and the unity of the science and practice in this field needs emphasis and accommodation. Finally, the importance of this subject has not lessened; it resides in the fact that control of the environment begins and ends with measurements: first, recognition that an unreasonable health risk is present, and last, assurance that the hazard has been abated. In between, measurements guide the application of engineering controls. To accomplish all of these objectives it is proposed that a symposium be convened during October-November 1991 at an eastern U.S. city with those who regulate and set standards together with users, designers, manufacturers, and vendors of instruments that are used for air sampling and analysis. It is anticipated that the symposium would encompass three major activities: 1. Presentations of invited and submitted technical papers on regulatory initiatives and setting of standards, measuring instruments, their operating principles, capabilities, feasible future improvements and applications, standards and performance criteria. 2. Exhibiting of commercial and laboratory-constructed instruments. 3. Formal technical workshops and clinics, scheduled and conducted by individual instrument manufacturers, to instruct and advise past and future purchasers how to use and get the most out of their equipment.